Champion ultimate manacost standardisation
A while ago a lot of champs got their ults manacosts set to 100 mana like all modern champs, riot stated that an ult should be limited by its cooldown and not also manacost.
Yet after some promising changes to champs you stopped while there are still a lot of champs whose ults cost a lot more then 100 mana, some even at level 1.
Example: Jarvan Vi Twitch Sona Veigar Karthus Twisted Fate Amumu Zilean Zyra Orianna Draven Warwick Skarner Singed Pantheon
Some people argued that for example Karthus ult would be to powerfull to have 100 manacost, but keep in mind it already has a 200s cooldown. Also counterpart ultimates have had their manacost reduced in the past (Brand, Viktor, Fiddle).
Could you do some testing and see if we could lower the ult manacosts of these champs to modern cost?
's Chronoshift and 
's Insanity Potion, might not even need a mana cost in the first place (Chronoshift is meant to be a clutch-save ult in the same manner as 
's Intervention, which is free, and Insanity Potion restores mana, so it makes little sense to consume mana in order to replenish it). If these changes somehow make these champions too powerful, it would be better to look at what makes each case too strong and balance it (at worst, just up the champion's mana cost or decrease their base mana or regen) than to stay with their current state of non-standard mana costs.
is the only example I can think of (Final Hour costs 80 mana), and I think she could easily be fine with just a base mana increase, or just no buff at all. Alternatively, considering her ultimate encourages her to get into very risky combat, I'd say it could even have its mana cost removed outright.